I'm really curious because on this link provided by stopcrazypp. http://www.nrel.gov/vehiclesandfuels/energystorage/pdfs/45048.pdf It may be possible to substantially increase battery life in warmer climates if the owner also has shorter trips (~35%-50% dod) and can modify the set-point to keep the batteries cooler. I imagine Tesla picked whatever temperature they use because the average cost of electricity may make lower target temps infeasible for anyone on the grid. So for most people the extra cost of cooling may be less than the extra cost of a new pack. However, those of us with solar panels have a different economic picture and may want to trade a little more electricity (install additional PV panels) for longer battery life.
With an 8 year warranty on the battery pack I think Tesla will do what's best for the battery health. Also how can you know the temperature of the battery cells at any given moment?
The battery pack set points appear to be set in the vehicle software. Model S Overall Thermal Management Tesla likely designed those set points based on battery life versus range and cost for the average consumer. A consumer who has a cheaper source of electricity than average (eg solar), and doesn't mind taking a range and/or performance hit in exchange for reducing battery capacity loss due to temperature may want to modify the thermal management to boost the pack's lifespan.
AMPd, Tesla does what it expects is the best average choice across all the most optimal choices for different users and circumstance. An individual user with tech knowledge then knows more. It would be great if new options were made available. Even if at a service center, specifically for such a driver, to optimize settings to his or her needs and situation